Note: Descriptions are shown in the official language in which they were submitted.
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ENGINE CONTROL UNIT
FIELD OF THE INVENTION
The present invention relates to an engine control unit of a jet propulsion
boat propelled by jetting water pressurized and accelerated by a water jet
pump.
BACKGROUND OF THE INVENTION
In a conventional type water jet bicycle, when a throttle (TH) angle of an
engine which drives a water jet pump and which is a propulsion engine is
changed, the speed of the engine is controlled in accordance with the
change (for example, refer to a patent document JP-A-2002-87390).
For example, when a throttle lever is operated and a throttle is turned
from a closed state into an open state, an engine control unit (ECU)
determines engine speed corresponding to a throttle angle in the state
based upon a value measured by another sensor and makes control over
the engine speed.
When the throttle is turned from the open state into the closed state, the
engine control unit similarly determines engine speed corresponding to
the throttle angle in the state and makes control over the engine speed.
This state will be described using a water jet bicycle in which a power
booster (a turbocharger) is provided to an engine that drives a water jet
pump as an example below.
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As shown in Fig. 5, the y-axis shows a value of each parameter such as
engine speed, a throttle angle, boost pressure and ignition timing and a
value on the upside of the y-axis is higher. The x-axis shows time.
In case as shown in Fig. 5, a throttle (TH) angle of the engine is held at a
predetermined value or more for fixed time, the engine speed is held in a
state of revolution (6400 rpm in Fig. 5) equal to or exceeding a
predetermined value for fixed time in accordance with this. When a
throttle angle of the engine rapidly narrows in short time in this state, the
engine speed similarly rapidly decreases. The boost pressure of the
turbocharger rapidly decreases as the engine speed decreases in a slight
time lag behind the engine speed and the ignition timing of engine fuel is
set to a value corresponding to decreased engine speed.
SUMMARY OF THE INVENTION
As described above, when the throttle is once closed, a throttle angle
narrows and even if engine speed is held high immediately before, the
engine speed decreases in accordance with the rapid closing of the throttle.
Therefore, even if a rider restores the throttle to full throttle acceleration
to accelerate again immediately after, the engine speed already rapidly
decreases and the ignition timing also lags. Therefore, a problem that the
responsibility of the boost pressure of the turbocharger is not satisfactory
and it takes time for the engine speed to reach a desired value again
occurs.
The invention is made in view of such a situation and the object is to
provide an engine control unit that can easily realize reacceleration in a jet
propulsion boat.
The invention is made to solve the problem and is characterized in that i n
the engine control unit of the jet propulsion boat that jets water
pressurized and accelerated by a water jet pump and is propelled by the
water, in case a throttle angle of the engine narrows in a state in which the
speed of an engine that drives the water jet pump is equal to or exceeds a
predetermined value, advance angle control is made over the ignition
timing of the engine.
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As advance angle control is made over the ignition timing of the engine
owing to such configuration in case a throttle of the engine is rapidly
closed exceeding a set value when the speed of the engine that drives the
water jet pump is in a state of revolution equal to or exceeding the
predetermined value, the rapid decrease of the engine speed can be
inhibited in case the engine speed is held high immediately before.
Besides, the invention is characterized in that in an engine control unit of
20 a jet propulsion boat that jets water pressurized a.nd accelerated by a
water
jet pump and is propelled by the water, in case a throttle angle of an
engine is a predetermined value or less in a state in which the speed of the
engine that drives the water jet pump is equal to or exceeds a
predetermined value, control is made so that the decxease of the engine
speed is inhibited for fixed time.
As the control is made so that the decrease of the engine speed is inhibited
for fixed time owing to such configuration in case the throttle angle of the
engine is the predetermined value or less when the speed of the engine
that drives the water jet pump is in a state of revolution equal to or
exceeding the predetermined value, the rapid decrease of the engine speed
can be securely inhibited in case the engine speed is held high
immediately before.
Besides, the invention is characterized in that in case a steering angle is a
predetermined value or less and a throttle angle of the engine is a
predetermined value or less, advance angle control is made over the
ignition timing of the engine.
Besides, the invention is characterized in that the engine is an engine
provided with a turbocharger.
As described above, according to the invention, as the rapid decrease of the
engine speed is inhibited in case the engine speed is held high
immediately before, effect that reacceleration can be easily realized in the
jet propulsion boat can be acquired.
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Besides, according to an aspect of the invention, as the rapid decrease of
the engine speed is securely inhibited in case the engine speed is held high
immediately before, effect that reacceleration can be securely realized in
the jet propulsion boat can be acquired.
BRIEF DESCRII''TIf~N OF THE DRAWINGS
Preferred embodiments of the invention are shown in the drawings,
wherein:
Fig. 1 is a side view a part of which is cut out showing a jet propulsion boat
mounting the engine control unit equivalent to this embodiment;
Fig. 2 is a plan showing the same jet propulsion boat;
Fig. 3 is a schematic perspective view mainly showing an engine and a
turbocharger;
Fig. 4 is a graph mainly showing the variation in time of engine speed and
ignition timing;
Fig. 5 is a graph showing the conventional type variation in time of
engine speed and ignition timing;
Fig. 6 is a flowchart showing the more concrete flow of advance angle
control over ignition timing;
Fig. 7 is a graph showing an advance angle correction amount;
Fig. 8 is a flowchart for calculating ignition timing; and
Fig. 9 is a graph showing the variation in time of an advance angle
amount of engine ignition timing since a flag is set.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, one embodiment of an engine control unit
according to the invention will be described below. Fig. 1 is a side view a
part of which is cut out showing a jet propulsion boat mounting the
engine control unit equivalent to this embodiment and Fig. 2 is a plan
showing the same boat.
As shown in these drawings (mainly Fig. 1), the jet propulsion boat 10 is a
saddle-type small-sized boat, a crew sits on a seat 12 on the body 11, and the
output of an engine 20 is adjusted by gripping and operating a steering
handlebar 13 with a throttle lever and adjusting an opening of a throttle
valve (not shown) of the engine 20.
The body of the boat 11 has floating structure acquired by bonding a hull 14
and a deck 15 and forming space 16 inside. In the space 16, the engine 20 is
mounted above the hull 14 and a water jet pump 30 as propelling means
driven by the engine 20 is provided to the rear of the hull 14.
The water jet pump 30 is provided with an impeller 32 arranged in a duct
18 extended from an intake 17 open to the bottom to a deflector 38 via an
exhaust nozzle 31 open to the rear end of the body, and a shaft (a drive
shaft) 22 for driving the impeller 32 is coupled to the output shaft 21 of the
engine 20 via a coupler 21a.
Therefore, when the impeller 32 is rotated by the engine 20 via the coupler
21a and the shaft 22, water taken in from the intake 17 is jetted from the
exhaust nozzle 31 via the deflector 38 and hereby, the body 11 is propelled.
The number of revolutions of the engine 20, that is, propelling force by the
water jet pump 30 is operated by the turning operation of the throttle lever
13a (see Fig. 2) of the steering handlebar 13. The deflector 38 is linked with
the steering handlebar 13 via operating wire not shown, is turned by the
operation of the handlebar 13 and hereby, a course of the body 11 can be
changed.
Fig. 3 is a schematic perspective view mainly showing the engine 20.
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The engine 20 is a DOHC-type in-line four-cylinder dry sump-type four-
cycle engine and its crankshaft (see the output shaft 21 shown in Fig. 1) is
arranged along the longitudinal direction of the body 11.
As shown in Figs. 1 to 3, a surge tank 41 and an inter-cooler 22 are
connected and arranged on the left side of the engine 20 in the traveling
direction F of the body 11 and an exhaust manifold 23 is arranged on the
right side of the engine 20.
A turbocharger 24 for feeding compressed intake air to the engine 20 is
arranged at the back of the engine 20 and an air cleaner case 40 for taking
new air in the turbocharger 24 via a pipe 25 is arranged in front of the
engine 20.
An exhaust outlet of the exhaust manifold 23 (see Fig. 2) is connected to a
turbine of the turbocharger 24. Besides, the inter-cooler 22 is connected to
a compressor of the turbocharger 24 via a pipe 22a and the surge tank 41 is
connected to the inter-cooler 22 via a pipe 21b. Therefore, after new air
from the air cleaner case 40 is supplied to the turbocharger 24 via the pipe
25, is compressed in its compressor and is supplied and cooled to/in the
inter-cooler 22 via the pipe.22a, the new air is supplied to the engine 20 via
the surge tank 41.
Exhaust gas which fulfills the role of turning the turbine of the
turbocharger 24 is exhausted into a water muffler 60 via a first exhaust
pipe 51, a back flow preventing chamber 52 for preventing the back flow of
wafer in a turnover (the penetration of water info the turbocharger 24 and
others) and a second exhaust pipe 53, and is further exhausted into a
stream made by the water jet pump 30 from the water muffler 60 via an
exhaust gas/waste water pipe 54 and a resonator.
An engine speed sensor that senses engine speed and a throttle angle
sensor that senses an angle of the throttle valve are provided to the engine
20. Besides, a boost pressure sensor that detects boost pressure is provided
to the turbocharger 24. The engine speed sensor, the throttle angle sensor
and the boost pressure sensor are connected to a controller 100 (engine
control unit) mounted in the jet propulsion boat 10.
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Measured values sensed by these sensors are regularly output to the
controller 100.
The controller 100 is an engine control unit (ECU) that controls the engine
20, the turbocharger 24 and others and is connected to a fuel injection
system and an igniter provided to the engine 20.
The fuel injection system injects fuel under the control of the controller
100. The igniter similarly ignites fuel under the control of the controller
100.
Next, referring to the drawings, the operation of the jet propulsion boat 10
in which the engine control unit equivalent to this embodiment is
mounted will be described.
Fig. 4 is a graph showing the variation in time of a value of each
parameter such as engine speed, a throttle angle, boost pressure and
ignition timing in the jet propulsion boat in which the engine control
unit equivalent to this embodiment is mounted as in Fig. 5. The y-axis
shows a value of the variation in time and a value on the upside of the y-
axis is higher. The x-axis shows time.
Suppose that the throttle valve of the engine 20 is held greatly open when
a rider grips the steering handlebar 13 provided with the throttle lever. At
this time, as shown in Fig. 4, as the throttle (TH) angle of the engine is
held at a predetermined value or at an angle equal to or larger than the
predetermined value for fixed time, the controller 100 controls the fuel
injection system and the igniter based upon a measured value of the
throttle angle output by the throttle angle sensor and holds the engine
speed in a state of revolution (6400 rpm in Fig. 4) equal to or exceeding the
predetermined value for fixed time.
Suppose that the throttle valve of the engine 20 is closed when the rider
suddenly releases the grip of the steering handlebar 13 provided with the
throttle lever in this state. When the throttle angle of the engine rapidly
narrows in short time, the controller 100 makes advance angle control
over the ignition timing of the igniter for fixed time using the decrease of
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a measured value of the throttle angle output by the throttle angle sensor
as a trigger. Concretely, the controller 100 detects that the ratio of the
decrease of the throttle angle calculated based upon the measured value of
the throttle angle output by the throttle angle sensor is equal to or exceeds
a predetermined value, corrects so that the ignition timing of the igniter is
earlier than ignition timing calculated based upon the engine speed for
fixed time and outputs an ignition signal to the igniter. Besides, at this
time, the controller 100 controls the quantity of fuel injected by the fuel
injection system based upon the result of the correction of the
corresponding ignition timing.
The fuel injection system injects fuel under the control of the controller
200 and the igniter ignites fuel according to an ignition signal output by
the controller 100 earlier than the top dead center of a piston.
Ignition timing is made earlier by such advance angle control over
ignition timing as shown in Fig. 4, compared with a case that no control is
made and the rapid decrease of the engine speed is inhibited, compared
with the case that no control is made.
When the rider grips the steering handlebar 13 provided with the throttle
lever in this state to make the throttle valve of the engine 20 greatly open,
the controller 100 calculates the engine speed based upon a measured
value of the throttle angle output by the throttle angle sensor and controls
the fuel injection system and the igniter so that the engine speed increases.
At this time, as the speed of the engine 20 is high, compared with the case
that no control is made, a response from the turbocharger 24 is acquired i n
a short time lag, the engine speed can be rapidly increased and the jet
propulsion boat 10 is easily accelerated again.
As described above, the engine control unit equivalent to this
embodiment makes advance angle control over the ignition timing of the
engine for fixed time and controls so that the decrease of the engine speed
is inhibited fox fixed time when the throttle angle of the engine narrows,
more concretely the ratio of the decrease of the throttle angle of the engine
is equal to or exceeds a predetermined value or. the throttle angle of the
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engine is equal to or less than a predetermined value in case the speed of
the engine that drives the water jet pump is held in a state of revolution
equal to or exceeding a predetermined value for fixed time and the throttle
angle of the engine is held at an angle equal to or exceeding a
predetermined value for fixed time.
Therefore, according to the jet propulsion boat mounting the engine
control unit equivalent to this embodiment, the responsibility of the boost
pressure of the turbocharger can be enhanced in reacceleration and the
engine speed reaches a desired value in short time again.
Therefore, effect that a desired acceleration feel is acquired according to
the
will of the rider who desires reacceleration is acquired.
Referring to the drawings, a second embodiment of the engine control
unit according to the invention will be described below. An engine
control unit equivalent to this embodiment is different from that in the
first embodiment in that it is more embodied how an advance angle
correction amount is set in the elapse of time. The description of a part
common to that in the first embodiment is omitted and a different part
will be described below.
Fig. 6 is a flowchart showing the more concrete flow of the advance angle
control of the ignition timing shown in Fig. 4.
Suppose that the throttle valve of the engine 20 is held greatly open when
a rider grips the steering handlebar 13 provided with the throttle lever. At
this time, as the throttle (TH) angle of the engine is held at a
predetermined value or at an angle equal to or larger than the
predetermined value for fixed time, the controller 100 controls the fuel
injection system and the igniter based upon .a measured , value of the
throttle angle output by the throttle angle sensor and holds the engine
speed in a state of revolution equal to or exceeding the predetermined
value for fixed time.
Suppose that the throttle valve of the engine 20 is closed when the rider
suddenly releases the grip of the steering handlebar 13 provided with the
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throttle lever in this state. When a throttle angle of an engine rapidly
narrows in short time, a controller 100 determines whether an advance
angle control flag is set or not using a fact that a measured value of the
throttle angle output by a throttle angle sensor is smaller than a threshold
value as a trigger (Yes in a step S1 shown in Fi.g. 6) (a step S2). As the
advance angle control flag is reset in an initial flag check (No in the step
S2), the controller 100 further determines whether the engine speed is
larger than a threshold value or not (a step S3). In this case, as the engine
is in a state in which it is revolved at high speed (Yes in the step S3), the
controller 100 sets the advance angle control flag (a step S4), retrieves an
advance angle correction amount table based upon the engine speed and
acquires an advance angle correction amount (a step S5).
In the meantime, in case the throttle angle is equal to or exceeds a
threshold value (No in the step S1) and in case the engine speed is equal to
or less than the threshold value (No in the step S3), the controller 100
resets the advance angle control flag, the advance angle correction amount
and the frequency of advances (steps S6, S7).
Fig. 7 is a graph showing the advance angle correction amount. In this
graph, the x-axis shows engine speed and a value is larger (shows higher
speed) on the right side on the x-axis. The y-axis shows the advance angle
correction amount of the ignition timing and a value is larger on the
upside on the y-axis. The advance angle correction amount has a preset
value depending upon engine speed in calculating the correction amount.
Concretely, the advance angle correction amount is set to a fixed lower
limit value up to a predetermined lower limit engine speed and when the
advance angle correction amount exceeds it, it is set to a higher value in
proportion to engine speed. Further, when the advance angle correction
amount reaches predetermined upper limit engine speed, the succeeding
advance angle correction amount is set to a fixed upper limit value.
Ignition timing is calculated using the acquired advance angle correction
amount of ignition timing (see Fig. 8). That is, tile controller 100
calculates
basic ignition timing based upon the advance angle correction amount of
ignition timing (a step S100 shown in Fig. 8) and outputs an ignition
signal to the igniter. At this time, the controller 100 also controls the
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quantity of fuel injected by the fuel injection system based upon the result
of the correction of ignition timing. The fuel injection system injects fuel
under control by the controller 100 and the igniter ignites fuel earlier than
the top dead center of the piston according to an ignition signal output by
the controller 100. Hereby, an advance angle correction amount at initial
time is reflected in the basic ignition timing and advance angle control is
made over the ignition timing of the igniter for fixed time.
Next, after fixed time elapses, the controller 100 calculates an advance
angle correction amount. That is, the controller 100 detects that a
measured value of the throttle angle output by the throttle angle sensor is
smaller than the threshold value (Yes in the step S1 shown in Fig. 6) and
determines whether the advance angle control flag is set or not (the step
S2). As the advance angle control flag is already set in the flag check at
this
time (Yes in the step S2), the controller 100 further determines whether
the frequency of advances is equal to or more than a set value or not (a
step S10). In the initial determination of the frequency of advances, the
frequency is reset and is smaller than the set value (No in the step S20).
Therefore, in this case, the controller 100 stores a number incremented by
one as the frequency of advances (a step S11), retrieves the advance angle
correction amount table based upon engine speed again and acquires an
advance angle correction amount (a step S12).
The controller 100 calculates the basic ignition timing based upon the
advance angle correction amount of ignition tuning again (the step S100
shown in Fig. 8) and outputs an ignition signal to the igniter. At this time,
the controller 100 also controls the quantity of fuel injected by the fuel
injection system based upon the result of the correction of the ignition
timing. The fuel injection system injects fuel under control by the
controller 100 and the igniter ignites fuel earlier than the top dead center
of the piston according to the ignition signal output by the controller 100.
Hereby, an advance angle correction amount after the advance angle
control flag is set is reflected in the basic ignition timing and advance
angle control is made over the ignition timing of the igniter for fixed time.
When a loop in the step S100 is executed up to the set value of the
frequency of advances (Yes in the step S10) in these steps S10 to S12, the
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controller 100 next subtracts the set value of the frequency of advances
from the advance angle correction amount (a step S20). In case an advance
angle correction amount after subtraction is zero or less (Yes in a step S21),
the controller 100 resets the advance angle control flag, the advance angle
correction amount and the frequency of advances (a step S22), calculates
the basic ignition timing in case the advance angle correction amount is
zero (the step S100 shown in Fig. 8) and outputs an ignition signal to the
igniter. At this time, the controller 100 also controls the quantity of fuel
injected by the fuel injection system based upon the result of the
correction of the ignition timing. The fuel injection system injects fuel
undex control by the controller 100 and the igniter ignites fuel according to
the ignition signal output by the controller 100. Hereby, an advance angle
correction amount after the advance angle control flag is reset is reflected
in the basic ignition timing and advance angle control over the ignition
timing of the igniter is released.
In the meantime, in case an advance angle correction amount after
subtraction is still larger than zero (No in the step S21), the controller 100
calculates the basic ignition timing based upon the advance angle
correction amount after subtraction (the step S100 shown in Fig. 8) and
outputs an ignition signal to the igniter. At this time, the controller 100
also controls the quantity of fuel injected by the fuel injection system based
upon the result of the correction of the ignition timing. The fuel injection
system injects fuel under control by the controller 100 and the igniter
ignites fuel earlier than the top dead center of the piston according to the
ignition signal output by the controller 100.
Hereby, an advance angle correction amount at initial time is reflected i n
the basic ignition timing and advance angle control is made over the
ignition timing of the igniter for fixed time.
The loop for subtraction in these steps S1, S2, S10 and S21 is executed until
an advance angle correction amount after subtraction is zero or less and
after the reset in the step S22, advance angle control over the ignition
timing of the igniter is released.
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Fig. 9 is a graph showing the variation in time of an advance angle
amount of the engine ignition timing since the flag is set. As shown i n
Fig. 9, the advance angle correction amount table is retrieved based upon
engine speed at each time every fixed time up to the set value of the
frequency of advances since the flag is set and an advance angle amount
after correction is determined. In the meantime, when the frequency of
advances reaches the set value, the advance angle correction amount is
subtracted by a set value of the frequency of advances every time and
when the advance angle correction amount is zero or less, the advance
angle control flag is reset.
The ignition timing is gradually restored after it is once made earlier by
such fine advance angle control over the ignition timing, compared with
the case that no advance angle control is made. Therefore, the rapid
decrease of the engine speed is inhibited, compared with the case that no
control is made.
When a rider grips the steering handlebar 13 provided with the throttle
lever in this state to make the throttle valve of the engine 20 greatly open,
the controller 100 calculates engine speed based upon a measured value of
the throttle angle output by the throttle angle sensor, controls the fuel
injection system and the igniter and enhances engine speed.
At this time, as the speed of the engine 20 is high, compared with the case
that no control is made, a response of the turbocharger 24 is acquired i n
short time lag, the engine speed can be rapidly enhanced and the jet
propulsion boat 10 is easily accelerated again.
As described above, in the engine control unit equivalent to this
embodiment, when the throttle angle of the engine is equal to or smaller
than a predetermined value in a state in which the speed of the engine
that drives a water jet pump is held in a state of revolution equal to or
exceeding the threshold value, the engine speed is controlled so that the
decrease of the engine speed is inhibited by making great advance angle
control over the ignition timing of the engine for fixed time and gradually
lowering an advance angle amount of the ignition timing up to zero after
the fixed time elapses.
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Therefore, according to the jet propulsion boat mounting the engine
control unit equivalent to this embodiment, the responsibility of the boost
pressure of the turbocharger in reacceleration can be enhanced and the
engine speed reaches a desired value in short time again.
Therefore, effect that a desired acceleration feel is acquired as the will of
the rider who desires reacceleration is acquired.
The embodiment of the invention is described above, however, the
invention is not limited to the embodiment and can be suitably
transformed in a range of the object of the invention.
Although various preferred embodiments of the present invention have
been described herein in detail, it will be appreciated by those skilled in
the
art, that variations may be made thereto without departing from the spirit
of the invention or the scope of the appended claims.
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